Cellular changes refer to alterations in the structure and function of cells, which can occur due to various factors such as aging, disease, or environmental influences. These changes can affect how cells grow, divide, and communicate with each other, impacting overall tissue and organ function. One common example of cellular changes is apoptosis, or programmed cell death, which is a natural process that helps maintain healthy tissue by removing damaged or unnecessary cells. Additionally, cancer involves significant cellular changes, where cells grow uncontrollably and evade normal regulatory mechanisms, leading to tumor formation.